Silver solders or brazing alloys and their use.

Abstract

The UK has hallmarking laws that govern the minimum amount of silver that must be present in solders for joining sterling silver. The minimum quantity is set at 65% silver. Many other countries allow solders with lower silver content of 55%. Higher silver solders usually have higher melting and working temperatures, which require higher levels of skill to use and can cause distortion and deep firestain in the piece being soldered: this can lead to increased and expensive finishing costs. Lower silver content solders offer lower melting and working temperatures, however a disadvantage is a decrease in the whiteness of the solder, which causes solder seams to become clearly visible on finished pieces, thus limiting the creative scope of the designer/maker.

Silver solders for jewellery and silverware have remained the same for at least 75 years. The challenge of this research was to provide solders that:

- conform to UK hallmarking laws - are easy to use, with low temperature flow properties that are normally found in the lower silver content solder alloys- have a good white colour to match the colour of Argentium Silver- have good tarnish resistant properties

The patent granted from this research and the commercial alloys produced by Stern-Leach in the USA derived from over 40 individual solder alloys, made and tested at Middlesex University. A range of paste solders has also been developed for furnace soldering operations.

Current work is being conducted with designer/makers in best utilising these new solders.